Automatic counting system for fluid suspended particle

ABSTRACT

A novel counting system for counting particles suspended in a fluid medium is disclosed. The counting system comprises electrode means for sensing the presence of particles in a fluid means and producing a signal representative thereof; conveying means for conveying the fluid medium through said electrode means into a measuring tube; an upper and a lower spaced apart fluid level sensing means disposed at the measuring tube; and counter means coupled with said sensing means and said electrode means for counting said signals, said counter means being turned on by said lower sensing means when the fluid reaches the lower level in the measuring tube, and being turned off by said upper sensing means when the fluid reaches the upper level in the measuring tube.

United States Patent AUTOMATIC COUNTING SYSTEM FOR FLUID SUSPENDEDPARTICLE 4 Claims, 4 Drawing Figs.

U.S. Cl 250/218, 250/222, 324/71 Int. Cl G0ln 21/26 Field ofSearch250/218,

222 (M); 73/1 13, 32, 432 (PC); 356/40, 39, 196, 197; 324/71 (PC), 710(PC); 235/92-30 (PC) Primary ExaminerWalter Stolwein Attorney-Werner W.Kleeman ABSTRACT: A novel counting system for counting particlessuspended in a fluid medium is disclosed. The counting system compriseselectrode means for sensing the presence of particles in a fluid meansand producing a signal representative thereof; conveying means forconveying the fluid medium through said electrode means into a measuringtube; an upper and a lower spaced apart fluid level sensing meansdisposed at the measuring tube; and counter means coupled with saidsensing means and said electrode means for counting said signals, saidcounter means being turned on by said lower sensing means when the fluidreaches the lower level in the measuring tube, and being turned off bysaid upper sensing means when the fluid reaches the upper level in themeasuring tube.

CONTROL AUTOMATIC COUNTING SYSTEM FOR FLUID SUSPENDED PARTICLEBACKGROUND OF THE INVENTION The present invention relates to an improvedcounting apparatus for counting particles suspended in a fluid medium,.wherein a respective quantity of the fluid medium which is tobemeasured together with the suspended particles is delivered by aconveying system from a container of the like through an electricalresistance measuring path. Each particle upon passing through theelectrical resistance measuring path causes a change of the measuringpath resistance which can be determined at a counting mechanism.

It has already been proposed in the art to measure the quantity of fluidmedium by means of a mercury siphon system in which mercury under theinfluence of the force of gravity in a vessel drops along avolumetrically calibrated path. Particle counters of this type arefrequently used for biological and medical tests, for instance for theroutine counting of blood cells or other cells. These mercury siphonsystems are cumbersome to operate, and upon rupture of the system thedanger exists that thereafter nocuous mercury vapors occur whichoriginate from mercury residues which have not been removed. If themercury siphon system is additionally employed for switching-in andswitching-out the countermechanism then the switching accuracy can beimpaired through the presence of contaminations or resulting mercuryoxide.

SUMMARY OF THE INVENTION Accordingly, it is a primary object of thepresent invention toprovide an "improved automatic particle countingsystem whicheffectively overcomes the aforementioned drawbacks existingin the previously considered prior art constructions.

Another more specific object of the present invention relates to animproved automatic particle counting system for theaccurate measurementof particles suspending in a fluid medium without the existence of theaforementioned dangers which might occur with the prior-artconstructions noted above.

Still another extremely significant object of the present inventionrelates to a particle counting system of the mentioned typewhichprovides for an exact measuring of the quantity of fluid mediumflowing through the electrical resistance measuring path without havingto employ the cumbersome and complicated mercury siphon system or amercury switching system.

Yet a further equally significant object of the present inventionrelates to an improved particle counting system which automaticallycounts particles suspended in a fluid medium in a completely accurateand reliable manner, wherein the system itself is relatively inexpensiveto manufacture, easy to operate, and not readily subject to breakdown.

Now, in order to implement these and still further objects of theinvention, which will become more readily apparent as the descriptionproceeds, theinventive automatic particle counting system is generallymanifested by the features that in order to measure the fluid mediumquantity flowing through the electrical resistance measuring path, thereare provided two photoelectric scanning devices which are arranged insuperimposed fashion at a predetermined distance from one another at avolumetrically calibrated measuring tube. These photoelectric scanningdevices utilize the sudden changes in intensity of the light impingingupon the corresponding photocell due to changes of the refractive andreflective conditions during passage of the fluid medium in order toswitchin and switch-out countennechanism mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be betterunderstood and objects other than those set forth above, will becomeapparent, when consideration is given to the following detaileddescription thereof. Such description makes reference to the annexeddrawings wherein:

FIG. I is a schematic sectional view of an embodiment of particlecounting apparatus;

FIG. 2 is an enlarged fragmentary view of a portion of the particlecounting apparatus depicted in FIG. 1, and in particular illustratingthe mode of operation of the photoelectric scanning or reading device atthe fluid level B of FIG. 1;

FIG. 3 is a block diagram of the electronic circuitry employed for theautomatic sequence of operating steps or operationalprogram of theparticle counting apparatus of FIG. 1; and

FIG. 4 is a block diagram of the electronic circuitry for the countingcircuit used in the particle counting apparatus of FIG. I.

DESCRIPTION OF THE PREFERRED EMBODIMENT Describing now the drawings, inFIG. I there is shown by way of example an embodiment of inventiveparticle counting apparatus essentially in sectional view. Such will beseen to comprise a measuring head embodying an electrode support member1 equipped with a substantially ring-shaped or annular outer electrode12 situated in an appropriately configured groove or recess 13.Furthermore, a substantially spiralshaped inner electrode I4 is arrangedin the bore 0 of the electrode support 1. The outer electrode 12 and'theinner electrode 14 are formed, for instance, from platinum or a platinumalloy. Furthermore, at the wall of the bore 0 of the electrode support 1there are additionally provided the peripheral grooves 15 and 16 servingto receive both the sealing O-rings l5 and 16', respectively.

A measuring path support member 2 also forming part of the measuringheads it detachably and exchangeably fitted into the bore 0 of theelectrode support 1. The measuring pat support member 2 is provided atits outer wall with a peripheral groove 21 serving to receive thesealing O-ring member 21'. In a bore 20 of the measuring path supportmember 2 there is mounted a crystal, here shown as a ruby 22, which, inturn, is provided with an orifice or bore 00 which forms the calibratedresistance measuring path. In order to count particles of differentsizes, it is possible to readily exchange the measuring path supportmember 2. Also, it might here be mentioned that the measuring pathsupport member 2 and the electrode support 1 are advantageously formedof an extensively chemically inert material, such as, for instance,TEFLON or ceramics.

Apart from the foregoing structure, the particle counting apparatusfurther embodies a glass tube 3 which is inserted with one end into thebore 0 of the electrode support 1. During operation of the system, apumping unit here shown as a hose pump P conveys fluid medium from acontainer 11 through the bore 00 of the ruby 22 into the glass tube 3.As best observed with reference to FIG. I, a leakage insert 34 providedwith the drain or bleed 35 can be connected to the hose member 33 of thehose pump P. The drain or bleed 35 serves to balance the negativepressure prevailing in the glass tube 3 and. in the hose member 33 whenthe pump P is switchedoff. On the other hand, by selecting the size ofthe bleed 35, it. is possible to influence the delivery capacity of thepump P.

As soon as the fluid column has passed through the level A, then pulsecounterrnechanism 42 is switched in through the agency of a controldevice 41 which, for instance, utilizes as its signal transmitter, aphotoelectric cell 44 provided with a lamp 46 and a shutter or diaphragm44. Pulse counter counterrnechanism then counts-the particles flowingthrough the measuring path defined by the bore 00 of the ruby 22. Asecond signal transmitter, again the the form of the photoelectric cell45 provided with the light source or lamp 47 and a shutter or diaphragm45, switches off the pulse countermechanism 42 as soon as the liquidcolumn passes through the level B. At the same time, a switching device43 changes the direction of rotation of the pump P'and therefore itspumping action. The fluid medium located in the glass tube 3 is ejectedvia the discharge tube 31 and flows into the collecting vessel orcontainer 17. The entire described counting operation is automatic assuch will become more fully apparent as the description proceeds. Theopening 30 of the discharge tube 31 is tightly sealed by a pressed-on,for example, spring-biased, sealing member 32, so that only fluid isdischarged, and no gas or fluid can be pumped in. The fluid mediumdischarged through the discharge tube 31 could also be directlydelivered back into the supply container or vessel 11, if desired.

The preceding description of the disclosed embodiment of particlecounting apparatus has been given in order to provide for a betterunderstanding of the invention, even though the primary subject matterof this disclosure is directed to'the scanning or readout mechanism andits associated electronic circuitry for performing the automaticcounting-operation. While the foregoing description is believed to beadequate for those varied in the art to readily understand the inventiveconcepts herein involved, reference may be further made to the commonlyassigned, copending U.S. application, Ser. No. 807,853, filed Mar.17,1969, and entitled: PARTICLE COUNTING APPARATUS, wherein there isdisclosed in even greater detail the physical construction of the hereinillustrated as well as other embodiments of particle counting apparatuswith which the automatic counting system of the invention can be readilyemployed.

Considering now FIG. 2, there is shown a photoelectric scanning orreadout device in fragmentary sectional view and its mode of operationat the fluid level B of FIG. 1. It has been assumed that no fluid mediumis present at the level B within the glass tube 3. A light ray R, whichimpinges upon the glass tube 3 through the apertured diaphragm orshutter 45', cannot enter the internal compartment 300 of the glass tube3 because of the total reflection conditions (wherein n,= refractiveindex glass-air; and 1 critical angle of incidence with respect to theperpendicular). Rather, this light ray R is reflected at the innercylindrical wall surface 310 and travels along the path R to impingeupon the photoelectric cell 45. The path of the light ray RR' for thiscase is shown in FIG. 2 with a solid line.

On the other hand, if the fluid medium reaches the level B, then thetotal reflection conditions (wherein n refractive index glass-fluid andI critical angle of incidence with respect to the perpendicular) at thecylindrical surface 310 are such that the light ray R moves along thepath R" into the internal compartment 300 and from this location againtravels through the glass wall of the tube 3 towards the outside. Inthis case, the light ray RR" no longer impinges upon the photocell 45.The photocell 45 must not be arranged such that its axis of symmetry isdirected towards the center of the glass tube 3. If the ratio of theouter diameter to the diameter of the hollow compartment of the glasstube 3 is chosen so that it amounts to approximately 3:1 and if there isselected a glass with a refractive index n=1.4 then, by utilizing thedescribed technique, it is possible to obtain without difficulty lightintensity variations which bring about more than a 50-fold change of thesignal of the photoelectric cell 45.

FIG. 3 shows in block diagram a preferred form of electric circuitry forthe inventive control device 41 of FIG. 1 for carrying out the automaticoperation of the sequential steps of the program. The system functionswith the operating voltage U,,. If the start button 51 is depressed,then the relay K, is energized via the contact a and assumes aselfholding action via the contacts a, a and the OR-gate 0,.Consequently, the following functions are triggered: The drive motor ofthe delivery or conveying pump P (FIG. 1) which is driven by the voltageU is switched-in via the contact c,. The conveying pump P should operatein such a fashion that fluid medium is sucked into the glass tube 3. Atthe same time, a voltage U is applied to the electrodes 12 and 14 ofFIG. 1. During this period of time no fluid medium is within the glasstube 3 between the levels A and B. Connected in series with thephotoelectric cells 44 and 45 are the respective amplifiers 441 and 451and the pulse shapers 442 and 452, respectively. The output signalfor'both pulse shapers is designated by reference character E.

As soon as the fluid medium has reached the level A within the glasstube 3, the output signal F appears at the pulse shaper 442.Consequently, at the output of the AND-gate A;,, there is fulfilled hecounting condition Z, since the inverter Y likewise inverts the outputsignal E of the pulse shaper 452 into the output signal F. The relay K,is now locked into its work position likewise via the AND-gate A, andthe OR-gate 0,. A time-delay mechanism ZV, which is likewiseelectrically coupled with the AND-gate A, prevents the occurrence ofundesired disturbances upon switching-in the light sources or la ps.

If the fluid medium passes through the upper level B, then, the relay Kis switched via the AND-gate A and the OR-gate 0 and assumes aself-holding condition via the contact a,, b and the OR-gate 0 At thesame time, the motor voltage U and the electrode voltage U are reversedin polarity at the contacts c and d and e and f The direction ofdelivery of the pump P is reversed. The current path a,, a 0, isinterrupted at the contact a,. Furthermore, the counting condition Z atthe output of the AND-gate A is no longer fulfilled. The pulse countermechanism 42 is switched-off.

Once the fluid medium has dropped beneath the level A, then the AND-gateA blocks and therefore also the OR-gate 0,. The relay K, returns intothe illustrated rest position. In consequence thereof, the relay Klikewise returns back into the illustrated rest position, because thecurrent path a,, b,,, 0 is interrupted. The system has again assumed thestationary starting condition. The invention also contemplates that theparticle counting apparatus automatically performs a predeterminednumber of counting periods.

FIG. 4 schematically illustrates an embodiment of the circuitry for thepulse counter mechanism 42 of FIG. 1. It will be observed that theelectrode potential U can be regulated by means of the potentiometer42a. The voltage changes or current changes produced during the flow ofparticles through the measuring path 00 (FIG. 1) are amplified in thepreamplifier 42b, attenuated or reduced in the attenuator 42c, and againamplified in the amplifier 42d. The thus obtained signal isstandardized, for instance in the form of a square wave pulse at theadjustable amplitude discriminator and pulse shaper 42c. The amplitudediscriminator and pulse shaper 42c can be constructed such thatadditionally, during a predetennined number of successive countingperiods, pulses in different predetermined amplitude ranges willautomatically be recorded. This, renders possible a completely automateddetermination of the size distribution of the particles. Thestandardized pulses which are to be counted are delivered to theAND-gate 42f. As soon as the control mechanism 41 (FIG. 1) delivers thecounting command in the form of the counting condition Z, the AND-gate42f for the standardized pulses which are to be counted becomesconductive. From a first scaler or divider 42g, the pulses which havebeen stepped down for instance times arrive via the second scaler ordivider 42h and the shunt path u to the switch 421'. From this switch42i, the counting pulses which, for instance, have now been stepped down1:100 and 121000 can be selectively delivered to the counter unit 42k.The counter unit 42k can be provided with connections for a printingunit by means of which the counting results can be recorded.

At the start of each counting period or interval, it is possible todeliver an extinguishing signal, for instance, from a monostablemultivibrator 42m via the terminal or connection I of the switch 42n tothe dividers 42g, 42h and the counter unit 42k. In the position III ofthe switch 42n, the counting results of a number of counting periods canbe added up. The

switch position lll can, for instance, only be attained via the counterposition II at which there is continuously present an extinguishingsignal. With this arrangement, it is possible to prevent summationerrors.

It should be apparent from the foregoing detailed description that theobjects set forth at the outset of this specification have now beensuccessfully achieved.

We claim: 1. A counting system for counting particles suspended in afluid medium, said system comprising:

electrode means for sensing the presence of particles in the fluidmedium and producing electrical signals representative thereof: ameasuringtube for receiving said fluid medium, the particles of whichare to be counted, said measuring tube being formed of alight-transmitting material: conveying means for conveying the fluidmedium past said electrode means into said measuring tube; a first and asecond fluid level sensing means disposed at said measuring tube inspaced relationship from one another; counter means coupled with saidfirst and second sensing means and said electrode means for countingsaid electrical signals, said counter means being turned-on by saidfirst sensing means when the fluid medium reaches a first level in saidmeasuring tube and being turned off by said second sensing means whenthe fluid medium reaches a second level in said measuring tube: eachsaid fluid level sensing means comprising a photocell and light source;and

means for mounting each respective photocell and light source at apredetermined angle from one another along the outside of aid measuringtube such that light from a given one of said light sources will impingeupon the respective associated photocell substantially only whensaid'measuring tube is devoid of fluid at the level of said respectivephotocell and light source and therefore being totally reflected at aninner glass-air boundary layer of said measuring tube.

2. A counting system as defined in claim further including reversingswitch means for said conveying means to effect drainage of the fluidmedium, said reversing switch means being coupled with said countermeans and being actuated when said counter means is turned ofi.

3. A system for counting particles suspended in a fluid medium, saidsystem comprising:

a light-transmitting measuring tube for receiving the fluid medium, theparticles of which are to be counted;

a measuring head supported at one end of said measuring tube, saidmeasuring head embodying electrode support means mounted at said one endof said measuring tube and a measuring path member possessing means forproviding at least one predetermined electrical resistance measuringpath defining at least one throughflow passageway for the fluid mediumfrom one side to the opposite side thereof:

electrode means supported by said electrode support means for sensingthe presence of particles in said fluid means as it moves through saidthroughflow passageway of said electrical resistance measuring path andfor producing electrical signals representative of the presence of saidparticles, said electrode means comprising a pair of electrodes mountedat said electrode support means for cooperation with opposite sides ofsaid through-flow passageway,

conveying means for conveying said fluid medium through said throughflowpassageway of said electrical resistance measuring path and past saidelectrode means into said measuring tube;

a first and a second fluid level sensing means disposed at saidmeasuring tube in spaced relationship from one another; counter meanscoupled with said first and second sensing means and said electrodemeans for counting said electrical signals, said counter means beingturned-on by said first sensing means when the fluid medium reaches afist level in said measuring tube and being turned off by said secondsensing means when the fluid medium reaches a second level in saidmeasuring tube;

each said fluid level sensing means comprising a photocell and lightsource: and

means for mounting each respective photocell and light source at apredetermined angle from one another along the outside of said measuringtube such that light from a given one of said light sources will impingeupon the respective associated photocell substantially only when saidmeasuring tube is devoid of fluid at the level of said respectivephotocell and light source and therefore being totally reflected at aninner glass-air boundary layer of said measuring tube.

4. The system as defined in claim 3, further including a switchingdevice responsive to signals transmitted by said second fluid levelsensing means for reversing the conveying direction of the fluid mediumby said conveying means.

2. A counting system as defined in claim 1, further including reversingswitch means for said conveying means to effect drainage of the fluidmedium, said reversing switch means being coupled with said countermeans and being actuated when said counter means is turned off.
 3. Asystem for counting particles suspended in a fluid medium, said systemcomprising: a light-transmitting measuring tube for receiving the fluidmedium, the particles of which are to be counted; a measuring headsupported at one end of said measuring tube, said measuring headembodying electrode support means mounted at said one end of saidmeasuring tube and a measuring path member possessing means forproviding at least one predetermined electrical resistance measuringpath defining at least one throughflow passageway for the fluid mediumfrom one side to the opposite side thereof: electrode means supported bysaid electrode support means for sensing the presence of particles insaid fluid means as it moves through said throughflow passageway of saidelectrical resistance measuring path and for producing electricalsignals representative of the presence of said particles, said electrodemeans comprising a pair of electrodes mounted at said electrode supportmeans for cooperation with opposite sides of said through-flowpassageway, conveying means for conveying said fluid medium through saidthroughflow passageway of said electrical resistance measuring path andpast said electrode means into said measuring tube; a first and a secondfluid level sensing means disposed at said measuring tube in spacedrelationship from one another; counter means coupled with said first andsecond sensing means and said electrode means for counting saidelectrical signals, said counter means being turned-on by said firstsensing means when the fluid medium reaches a fist level in saidmeasuring tube and being turned off by said second sensing means whenthe fluid medium reaches a second level in said measuring tube; eachsaid fluid level sensing means comprising a photocell and light source;and means for mounting each respective photocell and light source at apredetermined angle from one another along the outside of said measuringtube such that light from a given one of said light sources will impingeupon the respective associated photocell substantially only when saidmeasuring tube is devoid of fluid at the level of said respectivephotocell and light source and therefore being totally reflected at aninner glass-air boundary layer of said measuring tube.
 4. The system asdefined in claim 3, further including a switching device responsive tosignals transmitted by said second fluid level sensing means forreversing the conveying direction of the fluid medium by said conveyingmeans.